A semiconductor light emitting device, in general, is a body of a semiconductor material which when biased emits light, either visible or infrared, through the recombination of pairs of oppositely charged carriers Such devices generally include regions of opposite conductivity types forming a PN junction therebetween. When the junction is properly biased, charge carriers of one conductivity type are injected from one of the regions into the other where the predominant charge carriers are of the opposite conductivity type so as to achieve the light generating recombination.
An optical switch is an optoelectronic device that emits light in response to an optical input while an electrical bias is applied. One type of an optical switch is a body of a semiconductor material having four regions of alternating opposite conductivity type, i.e. PNPN or NPNP. Preferably the two interior regions are made of a direct-gap semiconductor material while the outer two regions are made of a wider-band-gap material. Such an optical switch is disclosed in U.S. Pat. No. 4,152,713 to John A Copeland, III et al, issued May 1, 1979 entitled UNIDIRECTIONAL OPTICAL DEVICE AND REGENERATOR. For certain types of optical communication or signal processing systems it is desirable to have an array of optical switches in which one or more of the switches can be selectively operated at one time. Although a plurality of the optical switch devices can be mechanically mounted together in an array, such an array would be relatively large and expensive to make. It is also possible to form an array of these optical switches on a single substrate to form a much smaller array. However, it has been found that such an array has a major problem. When one of the switching devices of the array is turned on by a light source, the voltage across all of the switching devices of the array will drop to a holding voltage. This holding voltage is low enough so that none of the other switching devices can be turned on. Thus, this type of an array is limited to having only one device turned on at a time. Therefore, it would be desirable to have an array of the switching devices in which one or more of the switching devices can be selectively turned on at any one time.